To investigate the activity of cyclophosphamide, 5-Fluorouracil, Estracyt, Streptozotocin, DTIC and procarbazine in advanced prostatic cancer. To determine if sequential therapy with these agents is useful clinically. To demonstrate their therapeutic effectiveness against current standard therapy. To determine the predictive value of the in vitro evaluation of chemotherapeutic agents (5-alpha reductase, arginase, DNA synthesis).